Pupillary motion observing apparatus

ABSTRACT

A television system using an infrared vidicon is used for displaying the pupil of a human eye to provide a measure of pupil size. Line scanning video signals scanned across the pupil may be monitored and clipped at a predetermined threshold level to determine the width of the pupil and therefore the area of the pupil. Line scans across the pupil are detected by an electronic system to provide an indication of pupil size.

United States Patent (72] Inventors Satoshi lshikawa Tokyo; Masao Okabe,llamamatsu; Yuji Hakamata, llamamatsu, all of, Japan [21] Appl. No.747,543 [22] Filed July 25, 1968 [45] Patented Aug. 10, 1971 [73]Assignee llarnamatsu T.V. Company, Limited Hamamatsn, Shizuoka, Japan[54] PUPILLARY MOTION OBSERVING APPARATUS I Claim, 6 Drawing Figs.

(52] US. Cl 128/2, 351/6, 351/7 [51] lnt.Cl A6lb3/l0 [50] Field ofSearch 128/2; 351/7, 6, 23, 39; 250/206, 221 220 [56] References CitedUNITED STATES PATENTS 3,525,565 8/1970 O'Neill et a1 351/6 2,445,7877/1948 Lilienfeld 351/7 2,573,464 10/1951 Lowenstein et al 351/73,036,568 5/1962 Stark 128/2 3,433,935 3/1969 Sherman 128/2 X 3,473,86810/1969 Young et al. 351/6 OTHER REFERENCES Feinberg, R., TransactionsOf The lntemational Opthalmic Optics Congress, 1961, publ. in London,1962, British Optical Assoc., pp. 268 273, RE951 I55, Lib. of Cong.(copy in GR. 250, 351/6) Roth; N., The Review Of Scientific instruments,Vol. 36, No. 11, Nov. 1965, pp. 1636- 1639, (copy in GR. 250, 351/6)Primary Examiner-Richard A. Gaudet Assistant Examiner-Kyle L. HowellAttorney-Laurence R. Brown MON! TOE 2 I I 8 I/ I! P .OA pEE 1 677072144742 ZED v g l g g PUPILLARY MOTION OBSERVING APPARATUS This inventionrelates to a pupillary motion observing apparatus.

The observation of the motion of a pupil is very important particularlyto the diagnosis of diseases in both ophthalmology and neurology fields.The overall observation of the pupil is generally inaccurate. In somecountries or particularly in America, there is a method of continuouslyphotographing it with an infrared film or observing it by using anoctovision. But there are shortcomings that no direct quantitativemeasurement value can be obtained without an enormous cost.

Therefore, an object of the present invention is to provide an apparatuswhereby the motion of a pupil can be recorded quantitatively without anytime delay.

Another object of the present invention is to provide a tiny inexpensiveapparatus whereby accurate medical examinations and diagnoses can bemade quickly without requiring any skill.

A further object of the present invention is to provide an ap- In thesynchronous signal polarity reverser 10, positive polarity pulses 32synchronized .with the synchronous signal 30 and having a largeamplitude somewhat wider than that of said signal will be superposed asshown in FIG. 4(a) and ([2). Therefore, if the trigger level is adjustedto be in the projecting part of the video signal, that is, in betweenthe parts 31 corresponding to the pupil 13, the Schmitt trigger circuit11 will send out square waves 33 as shown in FIG. 4 (c). The time widthT of this unit square wave is proportional to the time during which onescanning line, for example, a scanning line 14 scans the pupil I3 andtherefore to the distance I Further,

when a constant current circuit 15 is controlled with such square wavesignal as in FIG. 4 whenever each unit square wave is applied, aconstant current [will be able to be sent out of said circuit. As acondenser 16 is charged with said current I, the ten'ninal voltage ofthis condenser will increase with a fixed angle a of inclination foreach square wave in FIG. 4 (c) as in FIG. 4 (d). Whenever the imagepickup means 6 completes the scanning of one frame, the condenser 16will discharge the stored charge by reset circuit 18. Therefore, the

' voltage of the condenser 16 will be zero in the initial period ofparatus whereby it is not necessary to apply any mydriatic to eyes andtherefore no pain will be felt by the patient.

In the accompanying drawings:

FIG. 1 is a block diagram of an embodiment of the present invention;

FIG. 2 is a more detailed block diagram of an area detecting means ofthe apparatus in FIG. 1;

FIG. 3 is a view showing an optical image projected on a image pickupmeans by means ofthe apparatus in FIG. I;

FIG. 4 shown wave form diagrams for explaining the operation of theapparatus in FIG. I;

FIGS. 5 and 6 show examples of recorded curves observed with apparatusof FIG. I.

FIG. I shows an embodiment of theprcsent invention.

The eyeball 3 of a patient is illuminated in a dark room with a knowninfrared irradiating means such as an infrared filter 2 on a l. A Xenonflash 4 or 5 in a basic experiment are employed for the stimulus to thepupil. Further, ifa proper stimulation is given to the eye so that thepupil has contracted in a bright room, the pupil will gradually dilateto open in a dark room. The infrared image of pupil motion-is displayedon the photosensitive surface of an infrared image pickup means 6. Sincean infrared filter is provided in front ofthe image pickup means 6,irrespective of the visible rays of the xenon lamp 4 for dilating orcontracting the pupil by irradiation to the eye, an image of a fixedbrightness will be projected on the image pickup means 6 which sensesonly the rays of the infrared irradiating means. Therefore, the imagepickup means 6 will stably view the dilating or contracting motion ofthe pupil and will send out its video signal with vertical andhorizontal synchronous signals superposed on it. As those signals arefed into an area detecting means 7 and a monitoring device 8, the motionof the pupil can be observed with the monitoring device 8. In the areadetecting means 7, as shown in FIG. 2, the video signal applied from aterminal 9 will control a Schmitt trigger circuit I I through asynchronous signal polarity reverser I0. That is to say, if an image ofan eyeball as shown in FIG. 3 is projected on the photosensitive surfaceof the photosensitive surface of the image pickup means 6, the iris part12 and pupil 13 will be low in brightness. Therefore, if it is scannedwith any scanning line 14, there will be obtained a video signal of asubstantially inverted convex form as shown in FIG. 4 (a). Since theiris and pupil are circular, when the scanning line moves down, the timewidth of the above mentioned video signal in the scanning line willgradually increase to reach the maximum value and will again graduallydecrease. Further, between the respective unit video signals, ahorizontal synchronous signal of the inverse polarity to these signalswill be inserted as shown in FIG. 4 (b) and, at the same time, thoughnot illustrated, whenever the scanning of one frame is completed, avertical synchronous signal will be inserted. The form of thesesynchronous signals is the same as in general industrial televisionapparatus.

scanning one frame but will rise by the voltage proportional to thedistance I as the horizontal scanning line gradually lowers from theupper end of the photosensitive surface to cross the image 13 of thepupil and will reach the maximum value when the scanning line hasreached the lower end to complete the scanning of one frame. This valueis evidently proportional to the area of the image 13 of the pupil. Thisvoltage is amplified with a high input impedance amplifier l9 and isapplied to a memory circuit 2! through a switch circuit 20. The memorypulses generated from the memory pulse generating circuit 17 are appliedto the switch circuit 20 so that the switch circuit may be in aconducting state for a short time and transfers the voltage of thecondenser to the memory circuit 21 just before the reset is applied.

Further, the operation of the memory and the reset is practiced withinthe period of the vertical blanking pulse from generator 24. Wheneverthe scanning of one frame ends, the memory circuit 21 will memorize avoltage proportional to the area of the pupil and will hold thememorized value during the next period of one frame.

Since the output of this memory circuit 21 is amplified with as highinput impedance amplifier 22 and is applied to a recording system 23 asshown in FIG. 1, the dilation and contraction of the pupil will berecorded by a commercial recorder. For the recording, an analogautomatic balance recorder may be used. Further, when the output isapplied to a numerical value recording means through a proper analog todigital converter, it will be possible to type and record the area ofthe pupil at intervals ofa fixed time.

FIG. 5 shows a curve of the relation between the time t and pupil area Ain the case that the pupil was gradually dilated by giving a longerstimulus to the eyeball in which the pupil was contracted from a time 0to r as recorded with an automatic balance recorder in such apparatus asis described above. FIG, 6 shows an example of the same curve in thecase that the pupil was contracted by giving an irradiation to theeyeball in which the pupil was dilated from a time 0 to 1,. Therefore,for example, if a standard curve in each symptom is recorded in advanceand an observed curve is compared with it, an accurate diagnosis will bemade easily without any skill.

As has been explained in the above with reference to the describedembodiment of the present invention, such difficul ty as causing pain tothe patient when using conventional diagnosing methods can be eliminatedand, at the same time, an accurate observation of the pupil motion canbe made independent of visible rays irradiating the eyeball. Further,the changes of pupil area can be recorded quantitatively at the sametime without any time delay: ie a quick accurate diagnosis can be madewithout requiring any professional skill and furthermore, it is possibleto make a diagnosis mechanically by applying a measured value directlyto an electronic computer. The apparatus can be made simple, tiny andinexpensive.

What we claim is:

means extracting pupil signals-scanned across only the pupil out of thevideo scan signals produced by said image pickup means, meansintegrating the time widths of said pupil signals over each line scanpresentation during an entire frame period, and means for observing thevariation with time of said integrated pupil output signal of saidsignals.

1. Pupil motion observing apparatus comprising infrared irradiatingmeans for irradiating a pupil with infrared rays, infrared image pickupmeans for producing video signals of said pupil responsive to theinfrared rays irradiated on the pupil to thereby display the image ofthe pupil in video signal form, pupil area detecting means for obtainingsignals corresponding to the area of the pupil comprising means forprocessing said video signals scanned across the image of the pupil,means extracting pupil signals scanned across only the pupil out of thevideo scan signals produced by said image pickup means, meansintegrating the time widths of said pupil signals over each line scanpresentation during an entire frame period, and means for observing thevariation with time of said integrated pupil output signal of saidsignals.